This invention relates to an artificial snow wetting apparatus for carrying out snow deposition experiments in a strong wind by introducing the snowfall obtained by an artificial snow falling apparatus into an air channel and mixing an air flow flowing at a high velocity through the air channel with heated and humidified air prepared separately for wetting the snow, in order to use the snowfall obtained from the artificial snow falling apparatus for the snow deposition experiments.
The snow obtained by conventional artificial snow falling apparatuses is a dry snow and there has not been available any artificial snow falling apparatus which can provide a wet snow having an arbitrary moisture content.
In the case of a power cable, for example, snow is deposited on the cable during a snowfall and changes to what is known as "cylinder snow", which is subjected to torsion and causes problems such as breakage of the cable. This snow deposition occurs mostly when the snow is a wet snow carried by a strong wind, and the strong wind promotes the breakage of the cable.
Since an artificial snow wetting apparatus has not been available in the past as described above, fundamental snow deposition experiments to develop countermeasures have been carried out inevitably by granulating outdoor natural snow, wetting the snow by mist water or heating the snow and spraying the snow for deposition on the sample (cable) inside an air channel. However, the wet snow obtained by this method has different properties from those of natural snow with the result that a high correlationship cannot be established with snow deposition by the natural phenomenon. Moreover, it has been extremely difficult by this method to examine the relationship between the condition of the wet snow and the snow deposition phenomenon and to conduct other fundamental experiments.
The wet snow is formed under natural conditions in the following way. While the dry snow which is formed in a low temperature zone of a high atmospheric layer is falling, the surface of the snow crystal is partially melted to form water before the snow reaches the ground surface because the temperature and moisture increase with decreasing altitude, and this water covers the remaining snow crystal.
Therefore, the wet snow to be used for the snow deposition experiment must have a property such that the unmolten snow portion consists of the same crystal as that of the natural snow. The quantitative relationship between the water covering the surface of the crystal and the snow portion, that is, the moisture content, changes variously under natural conditions and for this reason, too, the wet snow having different properties under various conditions must be obtained freely and reliably for the purpose of the snow deposition experiment.
With reference to FIG. 1, when an attempt is made to wet the snow in a conventional artificial snow falling apparatus by heating and humidifying the lower part of an inner cylinder 3, which corresponds to an altitude near the ground surface in the natural environment, or the inner part of a test chamber 2, however, the air whose temperature is raised becomes an ascending current and rises inside the inner cylinder 3 so that a convection current occurs inside the inner cylinder in a corresponding way, a low temperature air layer at the upper part of the inner cylinder changes to a descending current against the flow velocity of a variable speed blower 6 and enters the test chamber 2. As a result, snow seed crystals will not grow to a suitable size and weight which becomes falling snow, and the snow cannot be wetted.
Accordingly, the development of a snow wetting apparatus capable of wetting snow obtained by an artificial snow falling apparatus has been desired particularly in the electric power industry in order to use the snow obtained by the snow falling apparatus for snow deposition experiments.